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McKenney" To: Oleg Nesterov Cc: Frederic Weisbecker , LKML , Boqun Feng , Joel Fernandes , Neeraj Upadhyay , Uladzislau Rezki , Zqiang , rcu , "Eric W . Biederman" , Lai Jiangshan Subject: Re: [PATCH] Revert "rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()" Message-ID: Reply-To: paulmck@kernel.org References: <20240425142404.19927-1-frederic@kernel.org> <20240429110328.GB1101@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240429110328.GB1101@redhat.com> On Mon, Apr 29, 2024 at 01:03:28PM +0200, Oleg Nesterov wrote: > On 04/25, Frederic Weisbecker wrote: > > > > This reverts commit 28319d6dc5e2ffefa452c2377dd0f71621b5bff0. The race > > it fixed was subject to conditions that don't exist anymore since: > > > > 1612160b9127 ("rcu-tasks: Eliminate deadlocks involving do_exit() and RCU tasks") > > > > This latter commit removes the use of SRCU that used to cover the > > RCU-tasks blind spot on exit between the tasklist's removal and the > > final preemption disabling. The task is now placed instead into a > > temporary list inside which voluntary sleeps are accounted as RCU-tasks > > quiescent states. This would disarm the deadlock initially reported > > against PID namespace exit. > > > > Signed-off-by: Frederic Weisbecker > > --- > > include/linux/rcupdate.h | 2 -- > > kernel/pid_namespace.c | 17 ----------------- > > kernel/rcu/tasks.h | 16 +++------------- > > 3 files changed, 3 insertions(+), 32 deletions(-) > > LGTM. FWIW, > > Reviewed-by: Oleg Nesterov Queued, thank you both! Thanx, Paul